The present invention relates to a method of carrying out transfer printing and also to print originals for the carrying-out of the method.
By transfer printing is meant a method in which images are produced by printing the release layer of a transfer material such as a transfer paper with conventional toner inks, low-viscosity inks, offset inks, flex inks or the like, then turning the printed side of the transfer material toward a substrate and transferring it to a substrate under the action of heat and pressure. The substrate may be a T-shirt and the transfer of the release layer may take place by ironing on under gentle pressure at 200° C. One such method is described in DE 10 2005 009 269, for example.
In this procedure the release layer, which may be a film laminated with the paper, becomes detached from the paper, and the film together with the printed image becomes joined to the substrate. A corollary of this procedure is that the polymeric film is transferred to the substrate even at those locations at which there are no imaging details or no printing inks, respectively. The transfer of the non-ink-bearing regions of the film sections as well is unwanted. The surface of the substrate may be impaired: a woven textile fabric, for instance, becomes more rigid and tends to develop small cracks, which in the case of relatively large film surfaces are conspicuous, particularly in the context of the non-ink-bearing areas. In order to have no excess film sections on the woven textile fabric, therefore, it will be necessary to punch or cut out the desired region to be transferred, a very onerous task.
For these purposes it is possible to use what are known as cutting plotters, where there are two areas of application: on the one hand, the cutting of uni-colored flex films which are offered in different colors, and on the other hand for the cutting of digital transfer films which are printed and contour-cut. Printers from the company Roland are able to print and contour-cut. Other printers (Mimaki, Mutoh, Seiko, HP) print with a first machine and cut the contour by means of a second machine, in which case the second machine must possess a register mark recognition system. The digital printing machines are becoming faster, i.e., the printing times are becoming shorter; however, the cutting operation is reaching physical limits, and in any case the non-print locations must be matrix-stripped manually. This is also not accomplished in one operation: for example, the inside parts of letters remain on the transfer film and must be taken out individually.
Materials such as paper or card are also suitable for enhancement by means of one kind of transfer printing: hot foil stamping. This method is used to enhance the value of a printed article by impressing ink-coated foils onto a paper or the card by means of pressure and heat. This method can also be employed in conjunction with relief printing.
The method requires high pressing pressures and enables an image to be applied, gloss or matt, to a printed article by means of the transferred film, depending on the type of film. As in the case of textiles it may be desirable here as well for only the printed regions together with the film to remain on the printed article.
Here as well, therefore, in order to avoid excess film regions, the images would have to be cut out by hand or by automatic units specifically intended for that purpose, in such a way that only the printed film areas are transferred to the substrate.